Excretion of potassium ion by prostanoic acid derivatives

ABSTRACT

Amethod for inducing decrease in potassium ion concentration in the blood which comprises administering, to a subject having an increased potassium ion concentration in the blood, a prostanoic acid derivative in an amount effective in inducing decrease in potassium ion concentration in the blood wherein said concentration is increased or for improving extracorporeal excretion of potassium ion in the blood which comprises administering, to a subject having an increased potassium ion concentration in the blood, a prostanoic acid derivative in an amount effective in improving extracorporeal excretion of potassium ion concentration is increased.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for improvement ofextracorporeal excretion of potassium ion and inducing decrease inpotassium ion concentration in the blood which comprises administering aprostanoic acid derivative to a subject.

The object of the present invention is to reduce potassium ionconcentration in the blood or improve extracorporeal excretion ofpotassium ion in the treatment of conditions wherein potassium ionconcentration in the blood is increased, e.g. hyperkalemia or renalinsufficiency. Generally, potassium ion in the blood is excreted intothe urine through the kidneys. According to the present invention,however, potassium ion is excreted through the intestinal wall as analternative main route, and this route is effective for a patient whoserenal function is reduced or injured. This method of excretion may becalled "intracorporeal dialysis".

Renal insufficiency refers to a condition in which renal function isinjured by renal diseases such as glamerulonephritis, nephroticsyndrome, nephrosclerosis, renal carcinoma, lupus nephritis etc. Oneimportant parameter for renal insufficiency is the excreting function ofkidney and especially the concentration of potassium ion in the bloodwhich are pooled in the body by injured excretion. Symptom ofhyperkalemia appears as the pooling progresses.

Traditional means effective in the treatment of renal insufficiency isthe so-called dialysis in which the blood is contacted with a dialysatewith a semipermeable membrane between them whereby substances in theblood may be removed through diffusion by osmotic gradient. The dialysisinclude hemokialysis in which the arterial blood is introduced into anartificial kidney and returned to a vein and peritoneal dialysis inwhich blood substances are dispersed into a dialysate, which isintroduced into the peritoneal cavity and discharged periodically,through capillary vessels serving as a semipermeable membrane. However,the former has disadvantage that it requires a sergical operation suchas shunt operation while the latter has disadvantages that it hasinferior dialysis efficacy and requires infection-preventing measures.

2. Background Information

The present invention and co-workers formerly discovered that15-keto-16-halo-prostaglandins (hereinafter, prostaglandin is referredto as PG) have an enteropooling activity (activity of pooling water inintestines) (EP-A-310305). Enteropooling activity of 16,16-dimethyl-PGE₂has also been described in Prostaglandins, 11, 809-828(1976). However,nothing has been reported about the fact that prostanoic acidderivatives have activity of excreting potassium ion.

As a result of extensive studies about the properties of PG compounds,the present inventors unexpectedly discovered that these compounds havean activity of decreasing potassium ion concentration in the blood andexcreting potassium ion.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a method for inducingdecrease in potassium ion concentration in the blood which comprisesadministering, to a subject having an increased potassium ionconcentration in the blood, a prostanoic acid derivative in an amounteffective in inducing decrease in potassium ion concentration in theblood wherein said concentration is increased.

In a second aspect, the present invention provides a method forimproving extracorporeal excretion of potassium ion in the blood whichcomprises administering, to a subject in need of such treatment, anamount, effective in improving extracorporeal excretion of potassium ionin the blood, of a prostanoic acid derivataive.

In a third aspect, the present invention provides a use of a prostanoicacid derivative for the manufacture of a medicament for inducingdecrease in potassium ion concentration in the blood.

In a fourth aspect, the present invention provides a use of a prostanoicacid derivative for the manufacture of a medicament for improvingextracorporeal excretion of potassium in the blood of a patient havingan increased potassium ion concentration in the blood.

In a fifth aspect, the present invention provides a pharmaceuticalcomposition for inducing decrease in potassium ion concentration in theblood comprising a prostanoic acid derivative in association with apharmaceutically acceptable carrier, diluent or excipient.

In a sixth aspect, the present invention provides a pharmaceuticalcomposition for improving extracorporeal excretion of potassium ion inthe blood of a patient having an increased potassium ion concentrationin the blood comprising a prostanoic acid derivative in association witha pharmaceutically acceptable carrier, diluent or excipient.

DETAILED DESCRIPTION OF THE INVENTION

The expression "extracorporeal excretion" means active or passivetransport of substances in the body fluid, principally in the blood,into the urine or feces through the intestine ranging from duodenum tolarge intestine, principally through small intestine.

The term "prostanoic acid" refers to the basic skeleton, show by theformula below, as the common structural feature of the naturallyoccurring PGs. ##STR1## The primary PGs are classified based on thestructural feature of the five-membered cycle moiety into PGAs, PGBs,PGCs, PGDs, PGEs, PGFs, PGGs, PGHs, PGIs and PGJs, and also on thepresence or absence of unsaturation and oxidation in the chain moietyas:

Subscript 1 - - - 15-OH

Subscript 2 - - - 5,6-unsaturated-15-OH

Subscript 3 - - - 5,6- and 17, 18-diunsaturated-15-OH

Further, PGFs are sub-classified according to the configration ofhydroxy group at 9 into α(hydroxy group being in the alpha configration)and β(hydroxy group being in the beta configration). Some syntheticanalogues have somewhat modified skeletons.

The term "derivative" refers to a compound in which one or more atom orgroup in the prostanoic acid shown by the formula (A) is replaced byother atom or group or eliminated. Such derivatization includes themodifications known in the synthetic PG analogues and othermodifications.

Nomenclature

Nomenclature of prostanoic acid derivatives herein uses the numberingsystem of prostanoic acid represented in formula (A) shown above.

While formula (A) shows a basic skeleton having a twenty carbon atoms,the 15-keto-PG compounds used in the present invention are not limitedto those having the same number of carbon atoms. The carbon atoms inFormula (A) are numbered 2 to 7 on the α-chain starting from theα-carbon atom adjacent to the carboxylic carbon atom which is numbered 1and towards the five-membered ring, 8 to 12 on the said ring startingfrom the carbon atom on which the α-chain is attached, and 13 to 20 onthe ω-chain starting from the carbon atom adjacent to the ring. When thenumber of carbon atoms is decreased in the α-chain, the number isdeleted in order starting from position 2 and when the number of carbonatoms is increased in the α-chain, compounds are named as substitutedderivatives having respective substituents at position 1 in place ofcarboxy group (C-1). Similarly, when the number of carbon atoms isdecreased in the ω-chain, the number is deleted in order starting fromposition 20 and when the number of carbon atoms is increased in theω-chain, compounds are named as substituted derivatives havingrespective substituents at position 20. Stereochemistry of the compoundsis the same as that of above formula (A) unless otherwise specified.

In general, PGDs, PGEs and PGFs have (a) hydroxy group(s) on the carbonatom(s) at position 9 and/or 11 but in the present specification PGsinclude those having a group other than a hydroxyl group at position 9and/or 11. Such PGs are referred to as 9-dehydroxy-9-substituted-PGcompounds or 11-dehydroxy-11-substituted-PG compounds.

As stated above, nomenclature of the prostanoic acid derivative is basedupon the prostanoic acid and sometimes utilizes abbreviation "PG" forconvenience, when the derivative in question has a partial structuralcommon with PGs. These compounds, however, can also be named accordingto the IUPAC naming system. For example,13,14-dihydro-15-keto-16R,S-fluoro-PGE₂ is(Z)-7-{(1R,2R,3R)-3-hydroxy-2[(4R,S)-4-fluoro-3-oxo-1-octyl]-5-oxocyclopentyl}-hept-5-enicacid. 13,14-dihydro-15-keto-20-ethyl-11-dehydroxy-11R-methyl-PGE₂ methylester is methyl7-{(1R,2S,3S)-3-methyl-2-[3-oxo-1-decyl]-5-oxo-cyclopentyl}-hept-5-enoate.13,14-dihydro-6,15-diketo-19-methyl-PGE₂ ethyl ester is ethyl7-{(1R,2S,3S)-3-hydroxy-2-(7-methyl-3-oxo-1-octyl)-5-oxo-cyclopentyl}-6-oxo-heptanoate.13,14-dihydro-15-keto-20-ethyl-PGF₂α isopropyl ester is isopropyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-{3-oxo-1-decyl)-cyclopentyl]hept-5-enoate.13,14-dihydro-15-keto-20-methyl-PGF₂α methyl ester is methyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-{3-oxo-1-nonyl}-cyclopentyl]-hept-5-enonate.

Preferred Compounds

Preferred prostanoic acid derivatives used in the present are thosehaving an oxo group at position 15 of the prostanoic acid in place ofthe hydroxy group, or having at least one halogen atom on the prostanoicacid skeleton, or having both of these features. These derivatives mayhave a single bond (15-keto-PG₁ compounds), a double bond (15-keto-PG₂compounds) between positions 5 and 6, or two double bonds (15-keto-PG₃compounds) between positions 5 and 6 as well as positions 17 and 18.

The term "halogen" refers to fluorine, chlorine, bromine and iodine withfluorine being preferred.

Examples of substitution products or derivatives include esters at thecarboxy group at the alpha chain, pharmaceutically or physiologicallyacceptable salts, unsaturated derivatives having a double bond or atriple bond between positions 2 and 3 or positions 5 and 6,respectively, substituted derivatives having substituent(s) on carbonatom(s) at position 3, 6, 16, 17, 19 and/or 20 and compounds havinglower alkyl or a hydroxy (lower) alkyl group at position 9 and/or 11 inplace of the hydroxy group, of the above PGs.

Examples of substituents present in preferred compounds are as follows:Substituents on the carbon atom at position 3, 17 and/or 19 includelower alkyl, for example, C₁₋₄ alkyl, especially methyl and ethyl.Substituents on the carbon atom at position 16 include lower alkyl e.g.methyl, ethyl etc., hydroxy and halogen atom e.g. chlorine, fluorine,phenyl and phenoxy, the last two being unsubstituted or substituted.Substituents on the carbon atom at position 20 include saturated andunsaturated lower alkyl e.g. C₁₋₄ alkyl, lower alkoxy e.g. C₁₋₄ alkoxyand lower alkoxy (lower)alkyl e.g C₁₋₄ alkoxy-C₁₋₄ alkyl Substituents onthe carbon atom at position 6 include oxo group forming carboxyl.Stereochemistry of PGs having hydroxy, lower alkyl or lower(hydroxy)alkyl substituent on the carbon atom at position 9 and/or 11may be alpha, beta or mixtures thereof.

Said derivatives may have an alkoxy, phenoxy or phenyl group at the endof the omega chain where the chain is shorter than the primary PGs.

In the present invention, preferred compounds are those having at leastone halogen atom on the prostanoic acid derivative, and the position ofhalogen atom is not limited but preferredly on the omega chain and morepreferredly one or two halogen atoms are present at position 16.

A group of preferred compounds used in the present invention has theformula (I) ##STR2## wherein X and Y are hydrogen, hydroxy, halo, loweralkyl, hydroxy(lower)alkyl, or oxo, with the proviso that at least oneof X and Y is a group other than hydrogen, and 5-members ring may haveat least one double bond, Z is hydrogen or halogen, A is --CH₂ OH,--COCH₂ OH, --COOH or is functional derivative, R₁ is bivalent saturatedor unsaturated, lower or medium aliphatic hydrocarbon residue which isunsubstituted or substituted with halo, oxo or aryl, R₂ is saturated orunsaturated, lower or mediumaliphatic hydrocarbon residue which isunsubstituted or substituted with oxo, hydroxy, halo, lower alkoxy,lower alkanoyloxy, cyclo(lower)alkyl, aryl or aryloxy, with the provisothe third carbon atom counted from 5-membered ring is substituted withan oxo group.

In the above formula, the term "unsaturated" in the definitions for R₁and R₂ is intended to include at least one and optionally more then onedouble bond and/or triple bond isolatedly, separately or seriallypresent between carbon atoms of the main and/or side chains. Accordingto usual nomenclature, an unsaturation between two serial positions isrepresented by denoting the lower number of said two positions, and anunsaturation between two distal positions is represented by denotingboth of the positions. Preferred unsaturation is a double bond atposition 2 and a double or triple bond at position 5.

The term "lower or medium aliphatic hydrocarbon residue" refers to astraight or branched chain hydrocarbyl group having 1 to 14 carbon atoms(for a side chain, 1 to 3 carbon atoms being preferred) and preferably 2to 8 carbon atoms for R₁ and 6 to 12 carbon atoms for R₂.

The term "halo" denotes fluoro, chloro, bromo and iodo.

The term "lower" is intended to include a group having 1 to 6 carbonatoms unless otherwise specified.

The term "lower alkyl" as a group or a moiety in hydroxy(lower)alkylincludes saturated and straight or branched chain hydrocarbon radicalscontaining 1 to 6, carbon atoms, e.g. methyl, ethyl, propyl, isopropyl,butyl, isobutyl, t-butyl, pentyl and hexyl.

The term "lower alkoxy" refers to the group lower-alkyl-O- wherein loweralkyl is as defined above.

The term "hydroxy(lower)alkyl" refers to alkyl as defined above andsubstituted with at least one hydroxy group, e.g. hydroxymethyl,1-hydroxyethyl, 2-hydroxyethyl and 1-methyl-1-hydroxyethyl.

The term "lower alkanoyloxy" refers to a group of the formula: RCO--O--wherein RCO-- is an acyl group formed by oxidation of a lower alkylgroup as defined above, e.g. acetyl.

The term "cyclo(lower)alkyl" refers to a cyclic group formed bycyclization of a lower alkyl group as defined above.

The term "aryl" includes unsubstituted or substituted aromaticcarbocyclic or heterocyclic (preferably monocyclic) groups, e.g. phenyl,tolyl, xylyl and thienyl. Examples of substituents are halo andhalo(lower)alkyl wherein halo and lower alkyl being as defined above.

The term "aryloxy" refers to a group of the formula: ArO-- wherein Ar isaryl as defined above.

The term "functional derivative" of carboxy as A includes salts(preferably pharmaceutically acceptable salts), esters and amides.

Suitable "pharmaceutically acceptable salts" includes conventionalnon-toxic salt, and may be a salt with an inorganic base, for example ametal salt such as an alkali metal salt (e.g. sodium salt, potassiumsalt, etc.) and an alkaline earth metal salt (e.g. calcium salt,magnesium salt, etc.), ammonium salt, a salt with an organic base, forexample, an amine salt (e.g. methylamine salt, dimethylamine salt,cyclohexylamine salt, benzylamine salt, piperidine salt, ethylenediaminesalt, ethanolamine salt, diethanolamine salt, triethanolamine salt,tris(hydroxymethylamino)methane salt, monomethyl-monoethanolamine salt,procaine salt, caffeine salt, etc.), basic amino acid salt (e.g.arginine salt, lysine salt, etc.), tetraalkylammonium salt and the like.These salts can be prepared by the conventional process, for examplefrom the corresponding acid and base or by salt interchange.

Examples of the esters are aliphatic esters, for example, lower alkylester e.g. methyl ester, ethyl ester, propyl ester, isopropyl ester,butyl ester, isobutyl ester, t-butyl ester, pentyl ester,1-cyclopropylethyl ester, etc., lower alkenyl ester e.g. vinyl ester,allyl ester, etc., lower alkynyl ester e.g. ethynyl ester, propynylester, etc., hydroxy(lower)alkyl ester e.g. hydroxyethyl ester, loweralkoxy(lower)-alkyl ester e.g. methoxymethyl ester, 1-methoxyetyl ester,etc., and aromatic esters, for example, optionally substituted arylester e.g. phenyl ester, tosyl ester, t-butylphenyl ester, salicylester, 3,4-di-methoxy-phenyl ester, benzamidophenyl ester etc.,aryl(lower)alkyl ester e.g. benzyl ester, trityl ester, benzhydrylester, etc. Examples of the amides are mono- or di- lower alkyl amidese.g. methylamide, ethylamide, dimethylamide, etc., arylamide e.g.anilide, toluidide, and lower alkyl- or aryl-sulfonylamide e.g.methylsulfonylamide, ethylsulfonylamide, tolylsulfonylamide etc.

Preferred examples of A include --COOH, --COOCH₃, --COOCH₂ CH₃,--COOCH(CH₃)₂) and --CONHSO₂ CH₃.

The configuration of the ring and the α- and/or omega chain in the aboveformula (I) may be the same as or different from that in the primaryPGs. However, the present invention also includes a mixture of acompound having a primary configuration and that of an unprimaryconfiguration.

Examples of the typical compounds of the present invention are15-keto-PGs, 13,14-dihydro-15-keto-PGs and their e.g.6-keto-derivatives, Δ² -derivatives, 3R,S-methyl-derivatives,16R,S-methylderivatives, 16,16-dimethyl-derivatives,16R,S-fluoroderivatives, 16,16-difluoro-derivatives,17S-methylderivatives, 19-methylderivatives, 20-methyl-derivatives and16-desbutyl-16-phenoxy derivatives.

When 15-keto-PG compounds of the present invention have a saturated bondbetween positions 13 and 14, these compounds may be in theketo-hermiacetal equilibrium by forming a hemiacetal between hydroxygroup at position 11 and ketone at position 15.

The proportion of both tautomeric isomers, when presnt, varies dependingon the structure of the rest of the molecule or kind of any substituentpresent and, sometimes, one isomer may predominantly be present incomparison with the other. However, in this invention, it is to beappreciated that the compounds used in the invention include bothisomers. Further, while the compounds used in the invention may berepresented by a structure or name based on keto-form regardless of thepresence or absence of the isomers, it is to be noted that suchstructure or name does not intend elimination of the hemiacetal type ofcompounds.

In the present invention, any of the individual tautomeric isomers, amixture thereof, or optical isomers, a mixture thereof, a racemicmixture, and other isomers such as steric isomers can be used in thesame purpose.

Some of the compounds used in the present invention may be prepared bythe method disclosed in Japanese Patent Publication (unexamined) No.A-52753/1989.

Alternatively, these compounds may be prepared by a process analogous tothat described herein or to known processes.

A practical preparation of the prostanoic acid derivative, e.g.13,14-dihydro-15-keto compounds, involves the following steps; referringto the synthetic charts(I) to (III), reaction of the aldehyde (2)prepared by the Collins oxidation of commercially available (-)-Coreylactone (1) with dimethyl (2-oxoheptyl)phosphate anion to giveα,β-unsaturated ketone (3), reduction of the α,β-unsaturated ketone (3)to the corresponding saturated ketone (4), protection of the carbonylgroup of the ketone (4) with a diol to the corresponding ketal (5), anddeprotection of the p-phenylbenzoyl group to give the correspondingalcohol (6) followed by protection of the newly derived hydroxy groupwith dihydropyrane to give the corresponding tetrahydropyranyl ether(7). According to the above process, a precursor of PGEs wherein theω-chain is a 13,14-dihydro-15-keto-alkyl group is prepared.

Using the above tetrahydropyranyl ether (7), 6-keto-PGE₁ s (15) of whicha group constituted with carbon atoms of position 5, 6 or 7 is --C₅ H₂--C₆ (O)--C₇ H₂ --, may be prepared in the following steps; reduction ofthe tetrahydropyranyl ether (7) with, for example, diisobutyl aluminumhydride to give the corresponding lactol (8), reaction of the lactol(8), with the ylide generated from (4-carboxybutyl)triphenyl phosphoniumbromide followed by esterification (10), cyclization between the5,6-double bond and the hydroxyl group at position 9 with NBS or iodineto give the halogenated compound (11), dehydrohalogenation of thecompound (11) with, for example, DBU to give the 6-keto compound (13)followed by Jones oxidation and removal of the protecting groups.

Furthermore, PGE₂ s (19) of which a group constituted with carbon atomsof position 5, 6 and 7 is --C₇ H₂ --C₆ H═C₅ H-- may be prepared in thefollowing steps; as shown in the synthetic chart II, reduction of theabove tetrahydropyranyl ether (7) to give the lactol (8), reaction ofthe resultant lactol (8) with the ylide derived from(4--carboxybutyl-)triphenyl phosphonium bromide to give the carboxylicacid (16) followed by esterification to give ester (17), Jones oxidationof the esters (17) to give the compound (18), and removal of theprotecting groups.

Using the above tetrahydropyranyl ether (7) as the starting material,the compound having --C₇ H₂ --C₆ H₂ --C₅ H₂ -- may be prepared by usingthe same process as that for preparing PGE₂ having --CH₂ CH═CH-- andsubjecting the resultant compound (18) to catalytic reduction to reducethe double bond between the position 5 and 6 followed by removal of theprotective groups.

Synthesis of 5,6-dehydro-PGE₂ s having --C₇ H₂ --C₆ .tbd.C₅ -- may becarried out by capturing a copper enolate formed by 1,4-addition of amonoalkylcopper complex or a dialkylcopper complex of the followingformulae: ##STR3## to 4R-t-butyldimethylsilyloxy-2-cyclopenten-1-onewith 6-alkoxycarbonyl-1-iodo-2-hexyne or the derivatives.

The 11-βtype PGEs can be prepared according to the synthetic chart III.

PGE derivatives having a methyl group at position 11 in place of hydroxycan be prepared by reacting a dimethyl copper complex with PGA-typecompound obtained by subjecting 9-hydroxy-11-tosylate to the Jonesoxidation. Alternatively, they can be prepared by protecting thecarbonyl of saturated ketone (4) produced by reducing unsaturated ketone(3), eliminating p-phenylbenzoyl and tosylating the produced alcohol,treating with DBU to form a lactol, introducing the alpha-chain byWittig reaction, oxidizing the alcohol at position 9 to give PGA-typecompound, and reacting the product with dimethyl copper complex in orderto introduce a methyl group into position 11 to give an11-methyl-PGE-type compound, which on reduction with e.g. sodiumborohydride gives an 11-methyl-PGF-type compound. An11-hydroxymethyl-PGE-type compound, is obtained by abenzophenone-sensitized photoaddition of methanol of PGA-type compound,which is reduced with, e.g. sodium borohydride, to give an11-hydroxymethyl-PGF-type compound. The synthetic route for thecompounds used in the present invention is not limited to the thatdescribed above one and may vary using different protecting, reducingand/or oxidizating methods.

Corresponding other PG compounds can be produced analogously. ##STR4##

The compounds used in the present invention may be used as a medicinefor animals and human beings and usually applied systemically or locallyby such methods as oral administration, intravenous injection (includinginstillation), subcutaneous injection, suppository and the like. Whilethe dosage will vary depending on the particular animal or humanpatient, age, body weight, symptom to be treated, desired therapeuticeffect, administration route, term of treatment and the like,satisfactory effects will be obtained with the dosage of 0.001-500 mg/kgadministered in 2 to 4 divided doses a day or as a sustained form.

As a solid composition of this invention for oral administration,tablets, troches, buccals, capsules, pills, powders, granules and thelike are included. The solid composition containing one or more activesubstances is mixed with at least an inactive diluent, e.g. lactose,mannitol, glucose, hydrocypropyl cellulose, fine crystalline cellulose,starch, polyvinyl pyrolidone, magnesium aluminate metasilcate. Thecomposition may contain additives other than the inactive diluent, forexample, lubricants e.g., magnesium stearae, a disintegrator e.g.cellulose calcium gluconates, stabilizers e.g. α-, β- orγ-cyclodextrins, etherated cyclodextrins (e.g. dimethyl-α- ,dimethyl-β-, trimethyl-β-, or hydroxypropyl-β-cyclodextrins), branchedcyclodextins (e.g. glucosyl- or maltosyl-cyclodextrins), formylcyclodextrins, sulfur-containing cyclodextrins, misoprotols orphospholipids. Such cyclodextrins may increase the stability of thecompounds by forming an inclusion compounds. The stability may be oftenincreased by forming lyposome with phospholipids. Tablets and pills maybe coated with an enteric or gastroenteric film e.g. white sugar,gelatin, hydroxypropylcellulose, hydroxypropylmethylcellulose phthalatesand the like, if necessary, and furthermore they may be covered with twoor more layers. Additionally, the composition may be in the form ofcapsules made of substance easily absorbed e.g. gelatin. The compositionmay be in the form of buccals, when an immediated effect is desired. Forthis purpose, base e.g. glycerine, lactose may be used.

Liquid compositions for oral administration include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups, elixirs and thelike and contain a generally used inactive diluent e.g. purified wateror ethyl alcohol. The composition may contain additives e.g. wettingagents, suspending agents, sweeteners, flavors, perfumes andpreservatives.

The composition of the present invention may be sprays which may containone or more active ingredients and which can be prepared according to awell known methods.

An injection of this invention for non-oral administration includesserile aqueous or nonaqueous solutions, suspensions, and emulsions.Diluents for the aqueous solution or suspension include, for example,distilled water for injection, physiological saline and Ringer'ssolution. Diluents for the nonaqueous solution and suspension include,for example, propylene glycol, polyethylene glycol, vegetable oils e.g.olive oil, alcohols, e.g. ethanol and polysorbates. The composition maycontain other additives, e.g. preservatives, wetting agents, emulsifyingagents, dispersing agents and the like. These are sterilized byfiltration through, e.g. a bacteria-retaining filter, compounding with asterilizer, gas sterilization or radiation sterilization. These can beprepared by producing a sterilized water or a sterilized solvent forinjection before use.

Another formulation according to the present invention is a rectal orvaginal suppository. This can be prepared by mixing at least one activecompound according to the invention with a suppository base e.g. cacaobutter and optionally containing nonionic surfactant for improvingabsorption.

The compounds used in the medicament according to the present inventionhave an effect of inducing decrease in potassium ion concentration or ofimproving excretion of potassium ion concentration in the blood into theintestines or as feces.

Accordingly, the compounds used in the present invention are useful fortreatment (e.g. prevention, cure, relief and arrest or relief ofdevelopment) of conditions wherein potassium ion level in the blood iselevated and of disorder in the balance of electrolytes such as uremiairrespective of cause, e.g. disease, drug or food.

A more complete understanding of the present invention can be obtainedby reference to the following Formulation Examples and Test Exampleswhich are provided herein for purpose of illustration only and are notintended to limit the scope of the invention.

Formulation Example 1 (Hard Gelatin Capsules)

13,14-dihydro-15-keto-16R,S-fluoro-PGE₂ : 50 mg lactose: 200 mg

The above ingredients were mixed and filled in hard gelatin capsules.

Formulation Example 2

    ______________________________________                                        (Powder, for injection)                                                                           (Parts by weight)                                         ______________________________________                                        13,14-dihydro-15-keto-16,16-difluoro-PGE.sub.2                                                      1                                                       mannitol              5                                                       distilled water         0.4                                                   ______________________________________                                    

The above ingredients were mixed, stirred, sterilized, filtered andlyophilized to give powders for injection.

Formulation Example 3

    ______________________________________                                        (Injectable solution)                                                                              (Parts by weight)                                        ______________________________________                                        13,14-dihydro-15-keto-16,16-dimethyl-PGE.sub.2                                                       0.2                                                    aomion surfactant      2                                                      distilled water        98                                                     ______________________________________                                    

The above ingredients were mixed and sterilized to give and injectablesolution.

Formulation Example 4

13,14-dihydro-15-keto-16,16-difluoro-20-ethyl-PGE₂ (50 mg) dissolved inmethanol (10 ml) was mixed with mannitol (18.5 g). The mixture wasscreened (with a sieve, the pore size of which being 30 mm in diameter),dried and screened again. The powders thus obtained were mixed withfine-grain silica gel (Aerosil*, 200 g) and filled in No.3 hard gelatincapsules (100) to give enteric capsules which contain 0.5 mg of13,14-dihydro-15-keto-16,16-difluoro-20-ethyl-PGE₂ per capsule.

Formulation Example 5

    ______________________________________                                        (Powders for oral administration)                                                                  (Parts by weight)                                        ______________________________________                                        13,14-dihydro-15-keto-16,16-difluoro-PGF.sub.2α                                                 5                                                     methyl ester                                                                  light anhydrous silicic acid                                                                          5                                                     Abicel ®           20                                                     lactose                70                                                     ______________________________________                                         ® Trade Mark                                                         

The above ingredients were mixed to give powders for oraladministration.

Formulation Example 6

    ______________________________________                                        (Soft gelatine capsules)                                                                           (Parts by weight)                                        ______________________________________                                        13,14-dihydro-15-keto-20-methyl-PGE.sub.2                                                             1                                                     methyl ester                                                                  light anhydrous silicic acid                                                                         899                                                    Panaste ®          20                                                     ______________________________________                                         ® Trade Mark                                                         

The above ingredients were mixed and filled in soft gelatine capsules.

Formulation Example 7 (Enteric capsules)

16-desbutyl-13,14-dihydro-15-keto-16-(m-trifluormethyl)phenoxy-PGF₂.alpha.methyl ester (50 mg) dissolved in methanol (10 ml) was mixed withmannitol (18.5 g). The mixture was screened (with a sieve, the pore sizeof which being 30 mm in diameter), dried for 90 minutes at 30° C. andscreened again. The powders thus obtained were mixed with fine-grainsilica gel (Aerosil*, 200 g) and filled in No.3 hard gelatin capsules(100) to give enteric capsules which contain 0.5 mg of13,14-dihydro-15-keto-16-desbutyl-16-m-trifluoromethylphenoxy-PGF₂.alpha.methyl ester per capsule.

In the above formulation examples, the active ingredient can be replacedby any other compound within the compounds used in the invention.

Test Example 1

Thirty male Crj: Wistar rats (5 weeks old, obtained from Charles River)were quarantined and acclimatized for about 1 weeks. Then the animalswere divided into groups with even mean weight and standard deviation.

All the animals were bred in individual stainless steel cages(190×380×180 mm) at a temperature of 24°±1° C. and with a humidity of55±5% with 12 hour light and dark cycle (illumination 8:00-20:00)supplying with fresh aseptic air. They were bred (with NMF, OrientalYeast Industries, Ltd) and waterad ad libitum exept the last day ofmedication, on which day they were fasted.

Test compound 13,14-dihydro-15-keto-16-R,S-fluoroprostaglandin E₂ wasdissolved in an aliquot of ethanol and the solution was evaporated in atest tube under nitrogen. The residue was combined with a predeterminedamount of distilled water and sonicated to form a homogeneous testsuspension.

Starting from day 1 to day 14, rats received (between 9:00 and 12:00) adaily dosage of 1 ml/1 kg of the test suspension through a disposableplastic sylinge (1 ml) equipped with an P.O. administration needle forrat based on the body weight measured just before the administration.

Design of the experiment was as follows:

    ______________________________________                                        Group      Dose (mg/kg)                                                                              Number of rats                                         ______________________________________                                        1          0           5                                                      2          0.1         5                                                      3          2.0         5                                                      ______________________________________                                    

All the animals were observed twice a day for any mortality and generalconditions such as diarrhea except the last day, on which observationwas made only once directly before the post mortem. The body weight andintake were measured every day at the predetermined time (between9:00-10:00) before the medication Urine collection (24 hr) was made 3hours after the medication under fasting on day 13.

Directly after the last medication, rats were sacrificed by cervicaldislocation and subjected to celiotomy. Intestine was ligated at pyloricpart of stomach and upper cecal part. The whole small intestine wasremoved and intraintestinal content was collected, measured a volume andcentrifuged for 5 minutes at 1000 rpm and suppernatant was separated.

The urine, serum and supernatant were assayed for electoylteconcentrations.

The results are summarized in the following Tables.

                                      TABLE 1                                     __________________________________________________________________________    Body weight                                                                          Weight (g)                                                             Dosage                                                                            Day                                                                              1   2   3   4   5   6   7   8   9   10  11  12  13  14                 __________________________________________________________________________    0   n  5   5   5   5   5   5   5   5   5   5   5   5   5   5                  (Con-                                                                             mean                                                                             277.7                                                                             282.0                                                                             291.9                                                                             296.2                                                                             307.3                                                                             312.3                                                                             320.4                                                                             329.7                                                                             334.9                                                                             340.8                                                                             346.4                                                                             350.1                                                                             356.0                                                                             318.0              trol)                                                                             S.D.                                                                             4.1 7.9 6.7 7.6 10.8                                                                              10.9                                                                              12.5                                                                              10.8                                                                              11.7                                                                              14.1                                                                              15.6                                                                              15.2                                                                              16.5                                                                              13.5               0.1 n  5   5   5   5   5   5   5   5   5   5   5   5   5   5                  mg/kg                                                                             mean                                                                             277.6                                                                             281.8                                                                             293.4                                                                             297.1                                                                             300.3                                                                             310.8                                                                             320.8                                                                             330.4                                                                             335.8                                                                             339.4                                                                             344.5                                                                             351.3                                                                             355.9                                                                             317.0                  S.D.                                                                             4.1 4.9 7.4 6.0 13.0                                                                              7.1 6.7 8.4 8.3 6.6 12.4                                                                              8.8 11.1                                                                              10.9               2.0 n  5   5   5   5   5   5   5   5   5   5   5   5   5   5                  mg/kg                                                                             mean                                                                             277.6                                                                             274.7                                                                             283.0                                                                             286.7                                                                             296.9                                                                             300.7                                                                             309.6                                                                             319.9                                                                             322.7                                                                             327.8                                                                             330.8                                                                             334.1                                                                             345.9                                                                             304.9                  S.D.                                                                             3.0 5.0 3.7 4.5 4.8 4.8 4.6 8.2 6.5 8.7 6.8 7.7 7.9 6.6                __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________    Intake                                                                                 Intake (g)                                                           Dosage                                                                              Day                                                                              1   2  3  4  5  6  7  8  9  10 11 12                                 __________________________________________________________________________    0     n  5   5  5  5  5  5  5  5  5  5  5  5                                  (Control)                                                                           mean                                                                             27.8                                                                              28.5                                                                             29.8                                                                             28.2                                                                             28.2                                                                             30.0                                                                             29.1                                                                             29.1                                                                             30.1                                                                             29.3                                                                             29.9                                                                             29.7                                     S.D.                                                                             3.1 2.6                                                                              2.6                                                                              1.9                                                                              3.0                                                                              2.1                                                                              2.4                                                                              2.4                                                                              2.7                                                                              3.1                                                                              2.1                                                                              2.9                                0.1 mg/kg                                                                           n  5   5  5  5  5  5  5  5  5  5  5  5                                        mean                                                                             25.9                                                                              28.6                                                                             29.1                                                                             24.4                                                                             29.3                                                                             30.7                                                                             29.5                                                                             29.3                                                                             28.8                                                                             29.4                                                                             29.1                                                                             28.6                                     S.D.                                                                             2.9 1.3                                                                              1.4                                                                              6.6                                                                              2.5                                                                              1.5                                                                              2.5                                                                              0.1                                                                              0.9                                                                              3.4                                                                              1.0                                                                              1.7                                2.0 mg/kg                                                                           n  5   5  5  5  5  5  5  5  5  5  5  5                                        mean                                                                             *19.3                                                                             24.8                                                                             26.1                                                                             25.2                                                                             26.3                                                                             28.1                                                                             29.0                                                                             27.8                                                                             28.7                                                                             29.1                                                                             28.0                                                                             30.9                                     S.D.                                                                             1.4 1.6                                                                              2.6                                                                              2.3                                                                              2.3                                                                              2.3                                                                              2.7                                                                              1.0                                                                              1.0                                                                              2.7                                                                              2.7                                                                              2.5                                __________________________________________________________________________     *0.05 > P > 0.01                                                              (DUNNET ANALYSIS)                                                        

                                      TABLE 3                                     __________________________________________________________________________    Electrolyte                                                                   (I.C.: Intraintestinal content)                                                           Urine                                                                             Na.sup.+                                                                             K.sup.+ Cl.sup.-                                                I.C.                                                                             (3 hr)                                                                            I.C.                                                                             Urine                                                                             I.C.                                                                              Urine                                                                             I.C.                                                                              Urine                                      Dosage   ml ml  mEq                                                                              mEq mEq mEq mEq mEq                                        __________________________________________________________________________    0     mean                                                                             2.2                                                                              3.9 0.38                                                                             0.17                                                                              0.022                                                                             0.30                                                                              0.148                                                                             0.175                                      (Control)                                                                           S.D.                                                                             1.2                                                                              2.1 0.17                                                                             0.09                                                                              0.010                                                                             0.16                                                                              0.082                                                                             0.121                                      0.1 mg/kg                                                                           mean                                                                             2.0                                                                              1.6 0.27                                                                             0.07                                                                              *0.045                                                                            0.20                                                                              0.172                                                                             0.125                                            S.D.                                                                             0.4                                                                              0.8 0.06                                                                             0.06                                                                              0.017                                                                             0.12                                                                              0.045                                                                             0.126                                      2.0 mg/kg                                                                           mean                                                                             *4.8                                                                             1.8 0.64                                                                             0.09                                                                              **0.096                                                                           0.12                                                                              **0.527                                                                           0.059                                            S.D.                                                                             1.8                                                                              1.0 0.25                                                                             0.06                                                                              0.027                                                                             0.05                                                                              0.217                                                                             0.033                                      __________________________________________________________________________     **0.1 > P                                                                     *0.05 > P > 0.01                                                              (DUNNET analysis)                                                        

From the above results, it can be easily understood that excretion ofpotassium ion into the intestine was dose-dependently increased in themedicated group. Almost no influence was observed in the medicated groupin respect to body weight and water intake.

Test Example 2

Male Wistar rats (8 weeks old) were anesthetized with pentobarbital (40mg/kg) and cortices of their left kidneys were partly removed. After 3to 7 days, their whole right kidneys were removed. The overall excisionof kidneys were 1 plus three fourth to 1 plus for fifth. As the testcompound, 13,14-dihydro-15-keto-16-R,S-fluoroprostaglandin E₂ methylester was suspended in distilled water and administered orally to thesurgically injured animals (3 per group) at a dose of 2 mg/kg/ml oncontinuous 14 days starting from the day after 14 days the operation.The dose was increased to 3 mg/kg on and after day 10 of administrationbecause animals can not to have diarrhea about that day. The controlgroup received the same volume of distilled water. One week after thestart of medication, blood samples were taken from tail vein of eachanimal and serum was assayed for Na, K and Cl concentrations.

In addition two weeks after the start of medication, the total blood wastaken from ventral aorta of each animal and serum was assayed for Na, Kand Cl concentrations. After 2 hours of the last medication, feces werecollected and extracted with a predetermined amount of distilled water.The extract was centrifuged and the supernatant was assayed forelectrolytes. Weight and water intake of the rats were measured atalmost daily.

The results are summarized in the following Table.

                  TABLE 4                                                         ______________________________________                                        Weight (g)                                                                                 Control group                                                                            Test group                                            Days of medication                                                                           mean   SD        mean SD                                       ______________________________________                                        0              332.2  33.3      341.7                                                                              23.9                                     1              345.9  35.3      321.8                                                                              24.3                                     2              324.0  23.0      311.8                                                                              15.7                                     3              345.4  25.7      313.8                                                                              10.8                                     4              339.4  22.5      319.3                                                                              10.3                                     5              344.9  25.1      336.7                                                                              12.8                                     7              352.7  31.0      351.6                                                                              15.5                                     8              348.9  25.7      341.9                                                                              17.4                                     9              335.6  26.0      341.0                                                                              15.6                                     10             360.6  32.8      348.6                                                                              23.5                                     11             360.6  21.1      359.6                                                                              20.3                                     12             355.2  28.2      356.7                                                                              17.1                                     13             357.9  27.2      359.5                                                                              20.2                                     14             337.7   8.6      364.8                                                                              15.0                                     ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Water intake (ml/day)                                                                      Control group                                                                            Test group                                            Days of medication                                                                           mean   SD        mean SD                                       ______________________________________                                        1              77.6   12.4      44.2 7.1                                      2              72.1   10.2      51.4 4.5                                      3                               48.3 13.7                                     4              69.0   10.2      66.3 16.3                                     5              74.6   9.5       99.8 18.3                                     8              70.6   5.1       99.8 18.3                                     9              73.4   7.0       95.9 16.1                                     10             75.4   5.0                                                     11             71.3   7.1       88.8 5.2                                      12             73.8   3.2       81.5 9.8                                      13             72.1   4.3       89.5 5.9                                      ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Serum                                                                         Group              Na        K      Cl                                        ______________________________________                                        untreated   mean   140.3     4.03   108.6                                                 ±SD ±5.4   ±0.21                                                                             ±2.9                                   2 weeks after                                                                             mean   142.6     4.42   104.0                                     operation   ±SD ±1.7   ±0.30                                                                             ±1.0                                   medicated   mean   141.7     3.79   104.4                                     control     ±SD ±5.6   ±0.69                                                                             ±3.8                                   1 week      mean   144.3     3.57** 107.1                                     medicated   ±SD ±1.8   ±0.66                                                                             ±2.4                                   medicated   mean   142.9     4.04   104.2                                     control     ±SD ±4.3   ±0.39                                                                             ±2.9                                   weeks       mean   147.5     3.32** 108.7                                     medicated   ±SD ±1.7   ±0.12                                                                             ±1.0                                   ______________________________________                                         *P < 0.05                                                                     **P < 0.1                                                                

                  TABLE 7                                                         ______________________________________                                        Serum                                                                                      control    2 mg/kg                                                            mean ± S.D.                                                                           mean ± S.D.                                        ______________________________________                                        Na      (mmol/l)   142.9 ± 4.3                                                                             147.5 ± 1.7                                K       (mmol/l)    4.64 ± 0.39                                                                             3.32 ± 0.12                               Cl      (mmol/l)   104.2 ± 2.9                                                                             108.7 ± 1.0                                ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Feces (2 weeks medication)                                                                     Na          K     Cl                                         group            mg          mg    mg                                         ______________________________________                                        control   mean   0.28        1.74  4.51                                       test      mean   14.01       21.46 40.35                                                ±SD ±10.35   ±6.35                                                                            ±11.03                                  ______________________________________                                    

For the above result, it can be clearly seen that, after two weeks ofrenal injury, potassium ion concentration in the blood was increased inthe injured group by about 10% as compared with the intact group andthat, after two weeks of the onset of medication, potassium ionconcentration was significantly decreased in the medicated group ascompared with the control group and further, 2 hours after themedication, electrolyte in feces of the medicated group were twelvetimes larger than in feces of the control group.

Test Example 3

The procedure of Test Example 2 was repeated except that13,14-dihydro-15-keto-16,16-difluoro-PGE₂ (1.0 mg/kg) was used as thetest compound. Contents of electorlyte in feces (after 5 days ofmedication) and in the serum (after 7 days of medication) are shown inthe following Tables.

                  TABLE 9                                                         ______________________________________                                        Feces                                                                         day                 Na mg    K mg   Cl mg                                     ______________________________________                                        5     Control    Mean   0.60   1.28   3.85                                                     S.D.   ±0.42                                                                             ±0.52                                                                             ±1.42                                      Medicated  Mean   4.47*  7.24** 13.57***                                                 S.D.   ±2.15                                                                             ±1.55                                                                             ±2.55                                ______________________________________                                    

                  TABLE 10                                                        ______________________________________                                        Serum                                                                         day               Na mmol/l  K mmol/l                                                                              Cl mmol/l                                ______________________________________                                        5    Control   Mean   139.4    10.09   105.2                                                 S.D.   ±2.1  ±1.60                                                                              ±1.5                                     Medicated Mean   141.1    9.22    105.4                                                 S.D.   ±3.4  ±0.60                                                                              ±3.8                                ______________________________________                                    

What we claimed is:
 1. A method for inducing decrease in potassium ionconcentration in the blood which comprises administering, to a subjecthaving an increased potassium ion concentration in the blood, .[.aderivative of a prostanoic acid having the skeleton.]. ##STR5## .Iadd.a15-keto-16-mono- or di-haloprostaglandin represented by formula (I).Iaddend.in an amount effective in inducing decrease in potassium ionconcentration in the blood .[.wherein said concentration isincreased.]..Iadd.: ##STR6##.Iaddend. wherein X and Y are independentlyselected from the group consisting of hydrogen, hydroxy, halo, loweralkyl, hydroxy(lower)alkyl and oxo, with the proviso that at least oneof X and Y is not hydrogen; the five-membered ring shown in structuralformula (I) may contain at least one double bond; Z is hydrogen orhalogen; A is --CH₂ OH, --COCH₂ OH, --COOH or a functional derivativethereof; R₁ is a bivalent saturated or unsaturated, lower or mediumaliphatic hydrocarbon residue which is unsubstituted or substituted withhalo, oxo or aryl; R₂ is a saturated or unsaturated, lower or mediumaliphatic hydrocarbon residue which is unsubstituted or substituted withoxo, hydroxy, halo, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl,aryl or aryloxy; R₂ contains at least four carbon atoms, with theproviso that the third carbon atom of R₂ removed from the five-memberedring being substituted with an oxo group and the fourth carbon atom ofR₂ removed from the five-membered ring being substituted with one or twohalogen atoms.
 2. The method according to claim 1, for compensatingreduced renal function.
 3. The method according to claim 1, for treatingrenal insufficiency. .[.4. The method according to claim 1, wherein theprostanoic acid derivative has one or two halogen atoms at position16..]. .[.5. The method according to claim 1, wherein the prostanoicacid derivative has an oxo group at position 15..].
 6. The methodaccording to claim 1, wherein the prostanoic acid derivative has asaturated bond between positions 13 and
 14. 7. The method according toclaim 1, wherein the prostanoic acid is a prostaglandin derivative. 8.The method according to claim 1, wherein the prostanoic acid derivativeis a 15-keto-16-mono- or di-fluoroprostaglandin compound.
 9. A methodfor improving extracorporeal excretion of potassium ion in the bloodwhich comprises administering, to a subject having an increasedpotassium ion concentration in the blood, .[.a derivative of aprostanoic acid having the skeleton.]. ##STR7## .Iadd.a 15-keto-16-mono-or di-haloprostaglandin represented by formula (I) .Iaddend.in an amounteffective in improving extracorporeal excretion of potassium ion.[.concentration is increased.]..Iadd.: ##STR8##.Iaddend. wherein X andY are independently selected from group consisting of hydrogen, hydroxy,halo, lower alkyl, hydroxy(lower)alkyl and oxo, with the proviso that atleast one of X and Y is not hydrogen; the five-membered ring shown instructural formula (I) may contain at least one double bond; Z ishydrogen or halogen; A is --CH₂ OH, --COCH₂ OH, --COOH or a functionalderivative thereof; R₁ is a bivalent saturated or unsaturated, lower ormedium aliphatic hydrocarbon residue which is unsubstituted orsubstituted with halo, oxo or aryl; R₂ is a saturated or unsaturated,lower or medium aliphatic hydrocarbon residue which is unsubstituted orsubstituted with oxo, hydroxy, halo, lower alkoxy, lower alkanoyloxy,cyclo(lower)alkyl, aryl or aryloxy; R₂ contains at least four carbonatoms, with the proviso that the third carbon atom of R₂ removed fromthe five-membered ring being substituted with an oxo group and thefourth carbon atom of R₂ removed from the five-membered ring beingsubstituted with one or two halogen atoms.
 10. The method according toclaim 9, wherein the excretion occurs through the intestine.
 11. Themethod according to claim 9, for treating hyperkalemia.
 12. The methodaccording to claim 9, for compensating reduced renal function.
 13. Themethod according to claim 9, for treating renal insufficiency. .[.14.The method according to claim 9, wherein the prostanoic acid derivativehas one or two halogen atoms at position 16..]. .[.15. The methodaccording to claim 9, wherein the prostanoic acid derivative has an oxogroup at position 15..].
 16. The method according to claim 9, whereinthe prostanoic acid derivative has a saturated bond between positions 13and
 14. 17. The method according to claim 9, wherein the prostanoic acidis a prostaglandin derivative.
 18. The method according to claim 9,wherein the prostanoic acid derivative is a 15-keto-16-mono- ordi-fluoroprostaglandin compound.
 19. The method according to claim 7wherein the derivative of a prostanoic acid is a PGA, PGB, PGC, PGD,PGE, PGF, PGG, PGH, PGI, or PGJ.
 20. The method of claim 17 wherein thederivative of a prostanoic acid is a PGA, PGB, PGC, PGD, PGE, PGF, PGG,PGH, PGI or PGJ.